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Photo of Saturn taken on May 8, 2016. Image captured through eyepiece projection method with a 4-in f/9 refractor, UV-IR filter, a 5 mm eyepiece, and a Logitech Pro 4000 web camera. Processed using AutoStakkert and Registax. To view the raw (unprocessed) images as captured by the web camera, click here.

The modest web camera (or webcam) quickly gained interest among amateur astronomers. It has two characteristics that are very much useful in astrophotography: (1) its lens can be removed much like the lens of a DSLR, making it possible to easily connect the webcam with any telescope and (2) it can record a huge number of still frames even in a short span of time (1-2 minutes), a feature particularly useful in a post-processing technique called registering and stacking. In this article, I intend to describe how to image planets using a web camera as the main imaging device and then provide a brief overview of the post-processing technique.

Two of the most popular webcams used in astrophotography: Logitech Pro 4000 (left) and Philips SPC900NC (right).

Any web camera may be used for astrophotography, some cameras however, perform better than others. Two of the most popular models are the Logitech Pro 4000 and the Philips SPC900NC, both of which are equipped with CCD sensors that produce far better images than other cameras of the same class, equipped with the less sensitive CMOS sensors.

Images may be captured using 2 different imaging techniques: (1) prime focus method and (2) eyepiece projection method. Details about each method and the accessories needed are described below.

Prime Focus

The prime focus method involves replacing the web camera’s lens with the lens (or mirror) of a telescope. The idea is to focus an image of the target (in this case, a planet) directly onto the web camera’s sensor. It requires a web camera (with the lens removed), a camera-to-telescope adapter, and a telescope.

Webcam imaging through prime focus method

In planetary imaging, it is important that the telescope has enough magnification to be able to capture considerable amount of detail. I recommend imaging at a focal length not less than 1000 mm. If your telescope is a bit too short, Barlow lenses may be inserted along the optical path to achieve longer focal lengths. Limit the number of Barlows to at most 2 to avoid image degradation, and as a general rule, always minimize the number of Barlows used — use one 4X Barlow lens instead of using two 2X Barlows stacked together.

Eyepiece Projection

The eyepiece projection method involves projecting an image onto the web camera’s sensor with the help of an eyepiece. This is a more complicated technique as it requires more adapters, but it tends to produce high-quality images. It requires a web camera (with the lens removed), a camera-to-telescope adapter, an eyepiece projection adapter, an eyepiece, and a telescope. It is advised, however, that you should learn prime focus imaging first before attempting eyepiece projection method.

Webcam imaging through eyepiece projection method

Using a higher-power eyepiece produces a larger image (higher magnification). Also, increasing the separation between the eyepiece and the sensor further increases the magnification. If higher magnification is desired, one may simply replace the eyepiece with a higher-power one, or increase the separation instead by using a tube extender. Barlows may serve as tube extenders provided that the ‘lens’ is removed.

A Barlow with the ‘lens’ removed. The metal tube may serve as an extender.

Image Processing

In planetary imaging, our goal is to record 2-3 minute videos of the planet we wish to image and then use a software to extract still image frames from this video (remember videos are just still images displayed in sequence), scroll through the frames and look for the best-looking image (sharp, clear, with lots of details), and then use the software to look for other images that are similar in quality. These frames will be aligned automatically and then combined to form one single image. Comparing all other frames one at a time with the best-looking image is called registering, while the process of putting all those similar frames on top of the other, aligning them automatically, and then combining all of them to form one single image is called stacking.

There are several freeware that can perform registering and stacking, one of which is called RegiStax. By registering and stacking images, sharp details are preserved, noise is greatly reduced, and the resulting image looks clean and smooth. The software may be downloaded here. I strongly suggest that you try to learn how to post-process recorded clips, I guarantee you will be amazed with the results!

Raw images captured by a webcam (as it appears on the recorded video in avi format)

Resulting photo after registering and stacking of thousands of raw images

For featured photos, click here.
For tutorials on how to get started with astrophotography, click here.
For DIY astronomy projects useful for astrophotography, click here.
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Hey, i’ve build a telescope using 20cm mirror on the bottom. and im using a webcam with its lens removed and without any of the adapter looking straight through a 45 degree slanted mirror down to the 20cm one with 600mm long, what i the magnifier of the image that webcam see? since there’s no lens on it anymore

HI, I have a logitec 4000 which I want to use for astroguiding and/or as a camera. However most of the adapters are for the SPC900NC. Do you know if the adaptors are interchangeable i.e. compatible screw threads?

Hi Andy, I am not sure if they do have exactly the same screw threads/specs, but in my case I am using simply the same adapter for both of my SPC900NC and Logitech 4000 web cameras. My best guess is that those commercially-available adapters for SPC900NC should also work for the Logitech 4000. Just be extra careful in screwing in the adapter. Clear skies!

I have tried using the Prime Focus method but the images I get are huge. One thing I tried with a different webcam was to keep the lens on it and keep the lens on the telescope also. I was able to see what I would see, but I don’t see this method used by anyone. Why would this not be favored by anyone? I tried to do the same with an HD webcam and I am having a very hard time lining it up just right with lenses and all in place. Any tips? Thx – Sergio

The method you are describing is called afocal imaging, wherein you use webcam with its lens, mounted on a telescope with an eyepiece. In any type of imaging, we try to minimize the number of optical elements between the object (e.g., the planet) and the camera’s sensor, since using more optical elements means more imperfections *may* be introduced in the final image. The simpler the setup is, the better. If you look at the afocal method, you’ll see that there are a lot of optical elements used which could introduce all sorts of problems related to the clarity of the image, which makes it less desirable. And even if you have superb optics, because of so many optical elements, less light will reach the sensor.

To minimize imperfections, other imaging techniques/methods may be employed. Just remember that as much as possible, you want to get larger ‘zoomed in’ images to allow you to get more details, regardless of the method used (of course within the practical limits of the steadiness of the atmosphere and the specs of your equipment). There are pros and cons, and you will have to try out each one and decide which ones will work best for you.

Thank you very much for taking the time to reply to me. What you say makes sense. I will experiment some more. With prime focus the image seems too big and blurred, it seems that my short 600mm refractor’s focal length is a problem. I tried Eyepiece projection and I can’t seem to focus the image, do I need more length beyond the focuser? In other words I probably need to put the webcam (with no lens) several inches away from the end of the eyepiece, correct?

In eyepiece projection, what I usually do is to center and focus the target first by looking directly through the eyepiece. Once centered and focused, I then mount the web camera (with its lens removed) immediately on top of the eyepiece. A fuzzy object then shows up in my monitor. Sharp focus is achieved by simply adjusting the focuser. Note however that sometimes focus travel is not enough (tube too short), thus, you’ll need to use a tube extender (I use Barlows with the ‘lens’ removed). I recommend doing a trial imaging session with the moon first before attempting to image a planet. Good luck!

Those are definitely the type of adapter you are looking for! Remember that what they are selling are simply the eyepiece projection adapter. You still need to purchase a webcam to telescope adapter (for use with webcams) or a T-ring plus T-adapter setup, if to be used with a DSLR. Good luck!

For the last two months here in South Ontario at night cloudy all night, did not get any clear sky at all. Hoping it will be in August if not only September and October should be good for watching at night. No luck for me so far.

hi I just bought a luminous 2 x.5 two inches barlow and one eyepiece Antares w70 series two inches 31mm with my skywatcher 150-750 black diamond which is very good to look, did I make a good choice need some advice

Don’t you need some kind of T-ring to webcam adapter for eyepiece projection? I have a standard 1.25″ camera adapter that holds eyepieces and has a T thread on the other end. With an eyepiece inserted there is no room to mount a webcam…

Hi Chumley, an ‘eyepiece projection adapter‘ solves that problem. It allows an eyepiece to connect to a focuser while and at the same time, allows a webcam to be attached to the eyepiece. Note that it also allows you to change the distance (separation) between the eyepiece and the web camera, which is very important in adjusting the size of the projected image. A larger distance or separation will yield a larger image.

hi Eteny what do you suggest using two inches barlow luminos 2x.5 with two inches eyepieces Antares 31mm is that a good choice to upgrade eyepiece and barlow for a skywatcher 150/750 6 inches diameter thanks for and answer

I have not used that particular Barlow, thus, I am unable to provide a concrete feedback. In any case, I do find a Barlow lens useful as it allows you to “zoom in” on planets every once in a while. For more info on Barlows, click here. Good luck!

This is a great article! I have been interested in webcam astrophotography for some time but most articles I read assume you have a refractor. I built an 8″ f7 a couple years ago and have been dying to see what kind of planetary shots I can get. I tried a couple webcams but it never really produced anything but frustration and disappointment. But now I’m thinking I had the lack of adjustment for the sensor distance. I’m going to vet back into this as soon as it starts to warm up. I did read somewhere to test the rig in the daytime, targeting a distant object to make sure webcam is aligned with eyepieces too.

I have a telescope like 150×700 star-tracker and have webcam. I try to attached a webcam along with the remove lance of the webcam with a adapter. I also attached cellphone along with OTG cabal and have a app also. Every thing are done but I can view any image on the display of my cellphone. Let me tell how I do the same? Hope your reply.

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